Honeyville has 5 sizes of High Efficiency ("HE") cyclones. The HE cyclones are similar to the Standard Series cyclones, but on a HE cyclone the straight side and cone heights are greater for increased material separation. In addition, the HE cyclones have a helical baffle between the straight side and inner vent tube to better direct the material down. MATERIAL: All welded hot rolled ("HR") carbon steel with butt seam constructionThree gauge thickness classifications available: Standard Duty, Heavy Duty, and Extra Heavy DutyOptional Materials: Abrasion Resistant ("AR") Steel, G90 Galvanized Steel, and Stainless SteelVENT: Each cyclone has a flanged vent for use with an Adjustable Vent Cap or a Return Air Manifold.ROOF: All sizes over 30" diameter have a 15 degree conical roof for greater vent tube stability.SAFETY RING: On MH36-HE and larger sizes, a safety ring mounted at roof edge is standard.EXTERIOR SURFACE: The exterior of cyclones made with HR or AR steel are finished with a base primer coat followed by a industrial alkyd enamel paint.CONE ACCESS DOOR*: 14" diameter, bolt-on panel, flush with the inside surface. *Standard on all cyclones 36" and larger. Optional 20" door panel is available.